diff --git a/racket/src/racket/src/error.c b/racket/src/racket/src/error.c
index f6a1c03108..ffb55e149f 100644
--- a/racket/src/racket/src/error.c
+++ b/racket/src/racket/src/error.c
@@ -4514,6 +4514,8 @@ scheme_raise_exn(int id, ...)
   Scheme_Object *eargs[MZEXN_MAXARGS], *errno_val = NULL;
   char *buffer;
 
+  rktio_remap_last_error(scheme_rktio);
+
   /* Precise GC: Don't allocate before getting hidden args off stack */
   HIDE_FROM_XFORM(va_start(args, id));
 
diff --git a/racket/src/racket/src/file.c b/racket/src/racket/src/file.c
index 2f88ea861e..622b8b615a 100644
--- a/racket/src/racket/src/file.c
+++ b/racket/src/racket/src/file.c
@@ -4634,9 +4634,9 @@ static Scheme_Object *filesystem_root_list(int argc, Scheme_Object *argv[])
   
   scheme_security_check_file("filesystem-root-list", NULL, SCHEME_GUARD_FILE_EXISTS);
 
-  roots = rktio_filesystem_root_list(scheme_rktio);
+  roots = rktio_filesystem_roots(scheme_rktio);
   for (i = 0; roots[i]; i++) {
-    v = scheme_make_pair(scheme_make_sized_offset_path(roots[i], strlen(roots[i]), -1, 1), scheme_null);
+    v = scheme_make_pair(scheme_make_sized_offset_path(roots[i], 0, -1, 1), scheme_null);
     if (last)
       SCHEME_CDR(last) = v;
     else
diff --git a/racket/src/racket/src/mzmark_port.inc b/racket/src/racket/src/mzmark_port.inc
index 0b5528b695..e8860adea2 100644
--- a/racket/src/racket/src/mzmark_port.inc
+++ b/racket/src/racket/src/mzmark_port.inc
@@ -97,7 +97,7 @@ static int mark_input_fd_MARK(void *p, struct NewGC *gc) {
   Scheme_FD *fd = (Scheme_FD *)p;
 
   gcMARK2(fd->buffer, gc);
-  gcMARK2(fd->refcount, gc);
+  /* fd->refcount is malloc()ed */
   gcMARK2(fd->flush_handle, gc);
   gcMARK2(fd->bufwidths, gc);
 
@@ -115,7 +115,7 @@ static int mark_input_fd_FIXUP(void *p, struct NewGC *gc) {
   Scheme_FD *fd = (Scheme_FD *)p;
 
   gcFIXUP2(fd->buffer, gc);
-  gcFIXUP2(fd->refcount, gc);
+  /* fd->refcount is malloc()ed */
   gcFIXUP2(fd->flush_handle, gc);
   gcFIXUP2(fd->bufwidths, gc);
 
diff --git a/racket/src/racket/src/mzmarksrc.c b/racket/src/racket/src/mzmarksrc.c
index 4118017551..1b861591d8 100644
--- a/racket/src/racket/src/mzmarksrc.c
+++ b/racket/src/racket/src/mzmarksrc.c
@@ -1736,7 +1736,7 @@ mark_input_fd {
   Scheme_FD *fd = (Scheme_FD *)p;
 
   gcMARK2(fd->buffer, gc);
-  gcMARK2(fd->refcount, gc);
+  /* fd->refcount is malloc()ed */
   gcMARK2(fd->flush_handle, gc);
   gcMARK2(fd->bufwidths, gc);
 
diff --git a/racket/src/racket/src/network.c b/racket/src/racket/src/network.c
index ca6e79a5da..2006869fee 100644
--- a/racket/src/racket/src/network.c
+++ b/racket/src/racket/src/network.c
@@ -40,6 +40,7 @@ typedef struct {
 typedef struct Scheme_Tcp_Buf {
   MZTAG_IF_REQUIRED
   short refcount;
+  short forget_on_close;
   char *buffer, *out_buffer;
   short bufpos, bufmax;
   short hiteof, bufmode;
@@ -462,7 +463,10 @@ static void tcp_close_input(Scheme_Input_Port *port)
 
   (void)scheme_rktio_fd_to_semaphore(data->tcp, MZFD_REMOVE);
 
-  rktio_close(scheme_rktio, data->tcp);
+  if (data->b.forget_on_close)
+    rktio_forget(scheme_rktio, data->tcp);
+  else
+    rktio_close(scheme_rktio, data->tcp);
 }
 
 static int
@@ -635,7 +639,10 @@ static void tcp_close_output(Scheme_Output_Port *port)
 
   (void)scheme_rktio_fd_to_semaphore(data->tcp, MZFD_REMOVE);
 
-  rktio_close(scheme_rktio, data->tcp);
+  if (data->b.forget_on_close)
+    rktio_forget(scheme_rktio, data->tcp);
+  else
+    rktio_close(scheme_rktio, data->tcp);
 }
 
 static int
@@ -741,6 +748,7 @@ static Connect_Progress_Data *make_connect_progress_data()
   pd->connect = NULL;
   pd->dest_addr = NULL;
   pd->src_addr = NULL;
+  pd->trying_s = NULL;
   pd->s = NULL;
 
   return pd;
@@ -1583,7 +1591,9 @@ void scheme_socket_to_ports(intptr_t s, const char *name, int takeover,
 
   rfd = rktio_system_fd(scheme_rktio, s, RKTIO_OPEN_READ | RKTIO_OPEN_WRITE | RKTIO_OPEN_SOCKET | RKTIO_OPEN_OWN);
 
-  tcp = make_tcp_port_data(rfd, takeover ? 2 : 3);
+  tcp = make_tcp_port_data(rfd, 2);
+  if (!takeover)
+    tcp->b.forget_on_close = 1;
 
   v = make_tcp_input_port(tcp, name, NULL);
   *_inp = v;
diff --git a/racket/src/racket/src/port.c b/racket/src/racket/src/port.c
index 26d960021d..2a377031de 100644
--- a/racket/src/racket/src/port.c
+++ b/racket/src/racket/src/port.c
@@ -4740,11 +4740,10 @@ fd_close_input(Scheme_Input_Port *port)
   fip = (Scheme_FD *)port->port_data;
 
   rc = adj_refcount(fip->refcount, -1);
-  if (!rc) {
+  if (!rc)
     rktio_close(scheme_rktio, fip->fd);
-  } else {
+  else
     rktio_forget(scheme_rktio, fip->fd);
-  }
 }
 
 static void
@@ -5327,6 +5326,7 @@ make_fd_output_port(rktio_fd_t *fd, Scheme_Object *name, int and_read, int flush
     Scheme_Object *a[2];
     rc = malloc_refcount(1, 1);
     fop->refcount = rc;
+    fd = rktio_system_fd(scheme_rktio, rktio_fd_system_fd(scheme_rktio, fd), rktio_fd_modes(scheme_rktio, fd));
     a[1] = the_port;
     a[0] = make_fd_input_port(fd, name, rc, 0);
     return scheme_values(2, a);
diff --git a/racket/src/racket/src/thread.c b/racket/src/racket/src/thread.c
index 4e8973c33a..7c60454e32 100644
--- a/racket/src/racket/src/thread.c
+++ b/racket/src/racket/src/thread.c
@@ -3916,6 +3916,8 @@ static int check_fd_semaphores()
   if (!scheme_semaphore_fd_set)
     return 0;
 
+  rktio_ltps_poll(scheme_rktio, scheme_semaphore_fd_set);
+  
   while (1) {
     h = rktio_ltps_get_signaled_handle(scheme_rktio, scheme_semaphore_fd_set);
     if (h) {
diff --git a/racket/src/rktio/rktio.h b/racket/src/rktio/rktio.h
index 60913649ea..6b1b6fbc69 100644
--- a/racket/src/rktio/rktio.h
+++ b/racket/src/rktio/rktio.h
@@ -153,7 +153,7 @@ RKTIO_EXTERN int rktio_fd_modes(rktio_t *rktio, rktio_fd_t *rfd);
 
 RKTIO_EXTERN rktio_fd_t *rktio_open(rktio_t *rktio, const char *src, int modes);
 /* Can report `RKTIO_ERROR_DOES_NOT_EXIST` in place of system error,
-   and can report `RKTIO_ERROR_UNSUPPORTED_TEXT_MODE` on Windows:=. */
+   and can report `RKTIO_ERROR_UNSUPPORTED_TEXT_MODE` on Windows. */
 
 RKTIO_EXTERN rktio_ok_t rktio_close(rktio_t *rktio, rktio_fd_t *fd);
 /* Can report `RKTIO_ERROR_EXISTS` in place of system error,
@@ -702,7 +702,7 @@ RKTIO_EXTERN void rktio_directory_list_stop(rktio_t *rktio, rktio_directory_list
 /* Interrupt a directory list in progress, not needed after
    rktio_directory_list_step() returns "": */
 
-RKTIO_EXTERN char **rktio_filesystem_root_list(rktio_t *rktio);
+RKTIO_EXTERN char **rktio_filesystem_roots(rktio_t *rktio);
 /* Returns a NULL-terminated array. Free each string. Currently never
    errors. */
 
@@ -822,6 +822,11 @@ enum {
 RKTIO_EXTERN void rktio_set_last_error(rktio_t *rktio, int kind, int errid);
 /* In case you need to save and restore error information. */
 
+RKTIO_EXTERN void rktio_remap_last_error(rktio_t *rktio);
+/* In a few cases, rktio substitutes a `RKTIO_ERROR_KIND_RACKET` error
+   for an OS-supplied error. This function can sometimes undo the
+   substitition, modifying the current error and kind. */
+
 RKTIO_EXTERN const char *rktio_get_last_error_string(rktio_t *rktio);
 RKTIO_EXTERN const char *rktio_get_error_string(rktio_t *rktio, int kind, int errid);
 /* The returned strings for `rktio_...error_string()` should not be
diff --git a/racket/src/rktio/rktio_envvars.c b/racket/src/rktio/rktio_envvars.c
index 17cf4b578d..09367c2e4f 100644
--- a/racket/src/rktio/rktio_envvars.c
+++ b/racket/src/rktio/rktio_envvars.c
@@ -9,6 +9,10 @@ struct rktio_envvars_t {
   char **vals;
 };
 
+#ifdef OS_X
+# define SETENV_DROPS_LEADING_EQUAL_SIGN
+#endif
+
 #if defined(OS_X) && !TARGET_OS_IPHONE
 # include <crt_externs.h>
 # define GET_ENVIRON_ARRAY *_NSGetEnviron()
@@ -85,8 +89,24 @@ int rktio_setenv(rktio_t *rktio, const char *name, const char *val)
 #ifdef RKTIO_SYSTEM_UNIX
   if (val) {
     int r;
+#ifdef SETENV_DROPS_LEADING_EQUAL_SIGN
+    char *tmp = NULL;
+    
+    if (val[0] == '=') {
+      intptr_t len = strlen(val);
+      tmp = malloc(len + 2);
+      memcpy(tmp + 1, val, len + 1);
+      tmp[0] = '=';
+      val = tmp;
+    }
+#endif
 
     r = setenv(name, val, 1);
+
+#ifdef SETENV_DROPS_LEADING_EQUAL_SIGN
+    if (tmp)
+      free(tmp);
+#endif
     
     if (r)
       get_posix_error();
diff --git a/racket/src/rktio/rktio_error.c b/racket/src/rktio/rktio_error.c
index fd4f69a94f..ba8d765c08 100644
--- a/racket/src/rktio/rktio_error.c
+++ b/racket/src/rktio/rktio_error.c
@@ -81,6 +81,22 @@ void rktio_set_last_error(rktio_t *rktio, int kind, int errid)
   rktio->errid = errid;
 }
 
+void rktio_remap_last_error(rktio_t *rktio)
+{
+  if (rktio->errkind == RKTIO_ERROR_KIND_RACKET) {
+    switch (rktio->errid) {
+    case RKTIO_ERROR_DOES_NOT_EXIST:
+#ifdef RKTIO_SYSTEM_UNIX
+      rktio_set_last_error(rktio, RKTIO_ERROR_KIND_POSIX, ENOENT);
+#endif
+#ifdef RKTIO_SYSTEM_WINDOWS
+      rktio_set_last_error(rktio, RKTIO_ERROR_KIND_WINDOWS, ERROR_FILE_NOT_FOUND);
+#endif
+      break;
+    }
+  }
+}
+
 const char *rktio_get_error_string(rktio_t *rktio, int kind, int errid)
 {
   const char *s = NULL;
diff --git a/racket/src/rktio/rktio_fs.c b/racket/src/rktio/rktio_fs.c
index cd6bdb1733..91e9b30b51 100644
--- a/racket/src/rktio/rktio_fs.c
+++ b/racket/src/rktio/rktio_fs.c
@@ -1630,7 +1630,7 @@ void rktio_copy_file_stop(rktio_t *rktio, rktio_file_copy_t *fc)
 /* filesystem root list                                                   */
 /*========================================================================*/
 
-char **rktio_filesystem_root_list(rktio_t *rktio)
+char **rktio_filesystem_roots(rktio_t *rktio)
 /* returns a NULL-terminated array of strings */
 {
 #ifdef RKTIO_SYSTEM_WINDOWS
@@ -1682,8 +1682,8 @@ char **rktio_filesystem_root_list(rktio_t *rktio)
   char **ss;
   
   ss = malloc(sizeof(char*) * 2);
-  ss[1] = strdup("/");
-  ss[0] = NULL;
+  ss[0] = strdup("/");
+  ss[1] = NULL;
 
   return ss;
 #endif